Component - Mixer V1.90 Datasheet.pdf

PSoC® Creator™ Component Datasheet
Mixer
1. 90
Features
 Single-ended mixer
 Continuous-time up mixing:
 Input frequencies up to 500 kHz
 Sample clock up to 1 MHz

Discrete-time, sample-and-hold down mixing:
 Input frequencies up to 14 MHz
 Sample clock up to 4 MHz


Adjustable power settings
Selectable reference voltage
General Description
The Mixer component provides a single-ended modulator. The Mixer component can be used for
frequency conversion of an input signal using a fixed Local Oscillator (LO) signal as the sampling
clock. The manipulations of signal frequencies that a mixer performs can be used to move
signals between frequency bands or to encode and decode signals. A mixer can be used to
convert signal power at one frequency into power at another frequency to make signal
processing easier, typically shifting higher frequencies to baseband. The mixer output is best
used by filtering the desired signal harmonics using an off-chip filter. Alternatively, the output can
be used to drive an on-chip ADC through internal routing. The component offers two
configurations:


Up mixer, continuous-time balance mixer, operates as a switching multiplier
Down mixer, discrete-time, sample-and-hold mixer
The component accepts two signals at different frequencies as inputs and outputs a mixture of
signals at multiple frequencies, including the sum and difference of the input signal and the local
oscillator signal. Typically, the unwanted frequency components in the output signal are removed
by filtering. A few examples illustrate the operation of the mixer in different modes.
Up Mixer: LO frequency greater than signal frequency
Shown with 100-kHz sine wave input, modulated by a 1.0-MHz Local Oscillator
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-79357 Rev. *A
Revised July 27, 2015
PSoC® Creator™ Component Datasheet
Mixer
The Up mixer is a multiplier. For signal frequency at FSIG and clock at FLO it generates a
modulated signal that is the product of the input and the LO. Because the LO is a square wave,
with all of its expected harmonics, the output has the form
FMOD ( t )  sin( 2FSIG )
 n sin(2F
1
LO t )
nodd
1
FMOD ( t ) 
2
 cos2nF
LO
 FSIG   cos2nFLO  FSIG 
In this case, the intended output is at FLO + FSIG and FLO – FSIG, as shown in the FFT below.
If a specific sideband, for example, FLO + FSIG, is required, the unwanted sideband can be filtered
out with active RC filters using the on-board opamps. You can also use the Filter component
after digitizing the Mixer output waveform.
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Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
Up Mixer: LO frequency less than signal frequency
Shown with input frequency of 455 kHz and LO of 430 kHz to yield a nominal output at 25 kHz.
The underlying sine wave at 25 kHz is apparent, but not obvious because the sum of 455 and
430 kHz appears at the same level.
The FFT for these waveforms clearly shows the input at 455 kHz, the output difference
frequency at the intended 25 kHz, and the sum output of the signal and first LO harmonic at
885 kHz. Just below the first harmonic's sum output is a term at 3 × FLO – FSIG or 835 kHz. The
pattern repeats with the term at 5 × FLO – FSIG just below 3 × FLO + FSIG. The miscellaneous “stuff”
between these well-known spectral lines is a function of the FFT, the windowing calculation
process, and the sin(x)/x nature of the sampling process. The look of these signals can change
depending on the type of spectrum analyzer used (swept spectrum versus FFT).
Down Mixer: LO near FSIG
When the LO frequency is near the signal frequency, a sampling mixer offers advantages over a
multiplying mixer. The time domain plot shows less higher-frequency content for harmonics of
the mixer. The steps at the sampling rate of the LO are readily apparent. The LO can be either
above or below the signal frequency, but the frequency distribution for LO > FSIG will be inverted
compared to the frequency distribution for LO < FSIG.
Document Number: 001-79357 Rev. *A
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Mixer
PSoC® Creator™ Component Datasheet
The mixing products are sin(x)/x related, so that when the sampling frequency (LO) is close to
the signal frequency, ‘x’ is close to . These terms are quite different from the 1/n harmonic
characteristic of the multiplying mixer. The harmonic content generated is substantially lower,
which means that higher-order terms are more easily filtered and eliminated.
The difference frequency between the signal and LO shows clearly in the FFT. Mix products near
the signal frequency are somewhat higher than the multiplying mixer, but all higher-order
harmonic terms are substantial.
When the LO frequency is above FSIG ÷ 2 or below FSIG × 1.5, substantial mix products appear
and the mixer loses its utility, it hardly separates the desired difference frequency from the mix
products.
Down Mixer: LO frequency less than FSIG/2
This is referred to as a subsampling mixer. When the LO frequency is less than half of the signal
frequency, the primary output is at FSIG – n × FLO where ‘n’ is the largest integer such that n × FLO
is less than FSIG. The waveforms for FSIG = 455 kHz and FLO = 143.3 kHz (= 430 kHz ÷ 3) show
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Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
that the primary output frequency is 25 kHz. The waveform is “coarser” than one with a higher
frequency LO, but the output frequency is the same as if the signal was sampled at a higher rate.
The advantage of the subsampling mixer is in the range of the allowed input signal frequency. It
is common to subsample by a factor of 4, so that a 13.57-MHz frequency can be sampled at
3.2 MHz to yield a primary output frequency of 770 kHz.
Over sampling mixers (for example, FSIG = 455 kHz and LO = 820 kHz) result in mixer products
similar to those of the multiplying mixer. These products may be more difficult to filter out of the
desired waveform.
Document Number: 001-79357 Rev. *A
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PSoC® Creator™ Component Datasheet
Mixer
Input/Output Connections
This section describes the input and output connections for the Mixer component. An asterisk (*)
in the list of I/Os indicates that the I/O may be hidden on the symbol under the conditions listed
in the description of that I/O.
Fin – Analog
Fin is the input signal terminal. The Fin signal is mixed with the local oscillator clock signal to
generate the Fout signal. Fin frequency is limited as follows:


Multiply (Up) mixer
Fin < 500 kHz
Sample (Down) mixer
Fin < 14 MHz
LO – Digital
LO is the local oscillator signal terminal. This signal serves as the sampling clock for the mixer.
The LO signal is mixed with the Fin signal to generate the Fout signal. For Multiply Mixer mode,
the LO clock signal must have a duty cycle of 50 percent.
LO frequency is limited as follows:


Multiply (Up) mixer
LO < 1 MHz
Sample (Down) mixer
LO < 4 MHz
Vref – Analog
Vref is the input terminal for a reference voltage. The reference voltage can be one of the PSoC
internal reference sources, an internal VDAC value, or an external signal.
Fout – Analog
Fout is the output signal terminal. The Fout signal is the resultant signal of the mixing operation
of the Fin and LO signals.
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Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
Component Parameters
Drag a Mixer component onto your design and double-click it to open the Configure dialog.
Mixer Type
This parameter determines the configured mode of the mixer SC/CT block. The component
supports two mixer modes: Multiply (Up) Mixer and Sample (Down) Mixer.
Power
This sets the initial drive power of the mixer. The power determines the speed with which the
mixer reacts to changes in the input signal. There are four power settings: Minimum, Low,
Medium (default), and High. A Low power setting results in the slowest response time and a
High power setting results in the fastest response time.
Document Number: 001-79357 Rev. *A
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PSoC® Creator™ Component Datasheet
Mixer
LO Frequency Setup
The Mixer can be connected to a clock source external to the component (External LO) or may
configure its own clock (Internal LO). If the LO is external, you must supply a 50-percent duty
cycle for Up mixers (Down mixers do not have this requirement). If the LO is internal, the
component derives the desired clock frequency with a 50-percent duty cycle for Up mixers. This
impacts the clock divider calculation. When changing a Mixer from Up to Down, or vice versa,
you may need to change the clock parameters to keep the Mixer operating properly in the Up
mode.
LO Frequency
This parameter sets the clock frequency when LO Frequency Setup is set to Internal LO. In the
Up mode, the terminating resistances in the mixer have values that are switched depending on
operating frequency to optimize performance. Lower LO Frequency values allow you to use
higher internal resistance values, resulting in slightly better modulator performance.
When LO Source is set to External LO, you must set the frequency in your external clock
(whether clock resource or digital block source).
Application Programming Interface
Application Programming Interface (API) routines allow you to configure the component using
software. The following table lists each routine and provides a brief functional description. The
subsequent sections cover each function in more detail.
By default, PSoC Creator assigns the instance name “Mixer_1” to the first instance of the
component in a given design. You can rename it to any unique value that follows the syntactic
rules for identifiers. The instance name becomes the prefix of every global function name,
variable, and constant symbol associated with the component. For readability, the instance name
used in the following table is “Mixer.”
Function
Description
Mixer_Start()
Powers up the Mixer.
Mixer_Stop()
Powers down the Mixer.
Mixer_SetPower()
Sets drive power to one of four levels.
Mixer_Sleep()
Stops and saves the user configuration.
Mixer_Wakeup()
Restores and enables the user configuration.
Mixer_Init()
Initializes or restores default Mixer configuration.
Mixer_Enable()
Enables the Mixer.
Mixer_SaveConfig()
Empty function. Provided for future use.
Mixer_RestoreConfig()
Empty function. Provided for future use.
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PSoC® Creator™ Component Datasheet
Mixer
Global Variables
Variable
Mixer_initVar
Description
Indicates whether the Mixer has been initialized. The variable is initialized to 0 and set to 1 the
first time Mixer_Start() is called. This allows the component to restart without reinitialization after
the first call to the Mixer_Start() routine.
If reinitialization of the component is required, then the Mixer_Init() function can be called before
the Mixer_Start() or Mixer_Enable() function.
void Mixer_Start(void)
Description:
Performs all of the required initialization for the component and enables power to the block.
The first time the routine is executed, the input and feedback resistance values are
configured for the operating mode selected in the design. When called to restart the mixer
following a Mixer_Stop() call, the current component parameter settings are retained.
Parameters:
None
Return Value:
None
Side Effects:
None
void Mixer_Stop(void)
Description:
Turns off the Mixer block.
Parameters:
None
Return Value:
None
Side Effects:
Does not affect mixer type or power settings
void Mixer_SetPower(uint8 power)
Description:
Sets the drive power to one of four settings; minimum, low, medium, or high.
Parameters:
uint8 power: See the following table for valid power settings.
Power Setting
Notes
Mixer_MINPOWER
Lowest active power and slowest reaction time
Mixer_LOWPOWER
Low power and speed
Mixer_MEDPOWER
Medium power and speed
Mixer_HIGHPOWER
Highest active power and fastest reaction time
Return Value:
None
Side Effects:
None
Document Number: 001-79357 Rev. *A
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PSoC® Creator™ Component Datasheet
Mixer
void Mixer_Sleep(void)
Description:
This is the preferred API to prepare the component for sleep. The Mixer_Sleep() API saves
the current component state. Then it calls the Mixer_Stop() function and calls
Mixer_SaveConfig() to save the hardware configuration.
Call the Mixer_Sleep() function before calling the CyPmSleep() or the CyPmHibernate()
function. Refer to the PSoC Creator System Reference Guide for more information about
power-management functions.
Parameters:
None
Return Value:
None
Side Effects:
None
void Mixer_Wakeup(void)
Description:
This is the preferred API to restore the component to the state when Mixer_Sleep() was
called. The Mixer_Wakeup() function calls the Mixer_RestoreConfig() function to restore the
configuration. If the component was enabled before the Mixer_Sleep() function was called,
the Mixer_Wakeup() function will also re-enable the component.
Parameters:
None
Return Value:
None
Side Effects:
Calling the Mixer_Wakeup() function without first calling the Mixer_Sleep() or
Mixer_SaveConfig() function may produce unexpected behavior.
void Mixer_Init(void)
Description:
Initializes or restores the component according to the customizer Configure dialog settings. It
is not necessary to call Mixer_Init() because the Mixer_Start() API calls this function and is
the preferred method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
All registers will be set to values according to the customizer Configure dialog.
void Mixer_Enable(void)
Description:
Activates the hardware and begins component operation. It is not necessary to call
Mixer_Enable() because the Mixer_Start() API calls this function, which is the preferred
method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
None
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Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
void Mixer_SaveConfig(void)
Description:
Empty function. Provided for future use.
Parameters:
None
Return Value:
None
Side Effects:
None
void Mixer_RestoreConfig(void)
Description:
Empty function. Provided for future use.
Parameters:
None
Return Value:
None
Side Effects:
None
Sample Firmware Source Code
PSoC Creator provides many example projects that include schematics and example code in the
Find Example Project dialog. For component-specific examples, open the dialog from the
Component Catalog or an instance of the component in a schematic. For general examples,
open the dialog from the Start Page or File menu. As needed, use the Filter Options in the
dialog to narrow the list of projects available to select.
Refer to the “Find Example Project” topic in the PSoC Creator Help for more information.
Functional Description
Mixer functionality is implemented using the PSoC SC/CT block. The discrete-time Down mixer
is implemented using the switched-capacitor mode. The multiplying (Up) mixer uses the
continuous-time block mode.
Discrete Time Down Mixer
The schematic for the internal configuration of the discrete time mixer is shown in Figure 1.
Document Number: 001-79357 Rev. *A
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PSoC® Creator™ Component Datasheet
Mixer
Figure 1. Discrete-Time Sample-and-Hold Mixer Schematic
The non-return-to-zero sample and hold is achieved by switching the integrating capacitor
between two capacitors. In Figure 1, either C1 or C4 can always be sampling the input signal
while the other is being integrated across the amplifier. The Fin signal is sampled at a rate less
than the FIN signal frequency. The mixer component is configured such that FOUT is integrated
with a new value on the rising edge of the input clock.
For LO sample clock frequencies greater than half of the FIN signal frequency, the output is the
difference between the input and LO frequencies plus aliasing components. When the sample
clock frequency is less than half of the FIN signal frequency, the output is the difference between
the input and the largest integer multiple of the LO frequency that is less than the FIN signal
frequency.
For a given input carrier frequency, FIN, a sample LO clock frequency, FCLK, can be chosen to
provide the desired output frequency, FOUT, for the system.
Provided that FCLK is less than 4 MHz, and FIN is less than 14 MHz:
If
2N  1
FCLK  FIN  N  FCLK , then
2
FOUT  N  FCLK  FI N
Equation 1
If
N  FCLK  FIN 
2N  1
FCLK , then
2
FOUT  FIN  N  FCLK
Equation 2
Equation 1 and Equation 2 can be summarized as:
FOUT  abs(N  FCLK  FIN )
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Equation 3
Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
Continuous-Time Up Mixer
The schematic for the internal configuration of the continuous-time mixer is shown in Figure 2.
Figure 2. Continuous-Time Mixer Configuration Schematic
In this mode, the opamp is configured as a PGA that uses the LO input signal to toggle between
an inverting PGA gain of 1 and a non-inverting unity gain buffer. The output signal includes
frequency components at FCLK ± FIN plus terms at odd harmonics of the LO frequency plus and
minus the input signal frequency: 3 × FCLK ± FIN, 5 × FCLK ± FIN, 7 × FCLK ± FIN, and so on.
FOUT  N  FCLK  FIN
with N holding odd values
Equation 4
Frequency Planning
Proper frequency planning is required to achieve the desired FOUT. The clocks must be carefully
controlled in the design-wide resources.
Resources
The Mixer component uses one SC/CT analog block.
API Memory Usage
The component memory usage varies significantly, depending on the compiler, device, number
of APIs used and component configuration. The following table provides the memory usage for
all APIs available in the given component configuration.
The measurements have been done with the associated compiler configured in Release mode
with optimization set for Size. For a specific design the map file generated by the compiler can
be analyzed to determine the memory usage.
Document Number: 001-79357 Rev. *A
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PSoC® Creator™ Component Datasheet
Mixer
PSoC 3 (Keil_PK51)
Configuration
Default
PSoC 5 (GCC)
PSoC 5LP (GCC)
Flash
SRAM
Flash
SRAM
Flash
SRAM
Bytes
Bytes
Bytes
Bytes
Bytes
Bytes
178
2
296
12
236
5
DC and AC Electrical Characteristics for PSoC 3
Specifications are valid for –40 °C ≤ TA ≤ 85 °C and TJ ≤ 100 °C, except where noted.
Specifications are valid for 1.71 V to 5.5 V, except where noted. Typical values are for TA = 25°C
DC Specifications
Parameter
VOS
G
Description
Conditions
Min
Typ
Max
Units
Input offset voltage
–
–
10
mV
Quiescent current
–
0.9
2
mA
Gain
-
0
-
dB
Min
Typ
Max
Units
AC Specifications
Parameter
Description
Conditions
FLO
Local oscillator frequency
Down mixer mode
–
–
4
MHz
FIN
Input signal frequency
Down mixer mode
–
–
14
MHz
FLO
Local oscillator frequency
Up mixer mode
–
–
1
MHz
FIN
Input signal frequency
Up mixer mode
–
–
1
MHz
SR
Slew rate
3
–
–
V/µs
DC and AC Electrical Characteristics for PSoC 5
Specifications are valid for –40 °C ≤ TA ≤ 85 °C and TJ ≤ 100 °C, except where noted.
Specifications are valid for 2.7 V to 5.5 V, except where noted. Typical values are for TA = 25°C
DC Specifications
Parameter
VOS
G
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Description
Conditions
Min
Typ
Max
Units
Input offset voltage
–
–
26
mV
Quiescent current
–
0.9
2
mA
Gain
–
0
–
dB
Document Number: 001-79357 Rev. *A
PSoC® Creator™ Component Datasheet
Mixer
AC Specifications
Parameter
Description
Conditions
Min
Typ
Max
Units
FLO
Local oscillator frequency
Down mixer mode
–
–
4
MHz
FIN
Input signal frequency
Down mixer mode
–
–
14
MHz
FLO
Local oscillator frequency
Up mixer mode
–
–
1
MHz
FIN
Input signal frequency
Up mixer mode
–
–
1
MHz
SR
Slew rate
3
–
–
V/µs
Component Changes
This section lists the major changes in the component from the previous version.
Version
Description of Changes
1.90.a
Minor datasheet edit.
1.90
Added all APIs with the
CYREENTRANT keyword when they
are included in the .cyre file.
Reason for Changes / Impact
This change is required to eliminate compiler warnings for
functions that are not reentrant used in a safe way:
protected from concurrent calls by flags or Critical
Sections.
Added PSoC 5LP support.
1.80
1.70
Updated customizer to avoid
overlapping of configure window labels
and controls across different DPI
settings.
Labels and text were overlapped in the old version of
Mixer.
Updated customizer to prevent the user
from entering invalid values for LO and
Signal frequencies
Customizer was not responding to user entries when
invalid frequencies are provided for LO and Signal
frequencies.
Mixer_Stop() API changes for PSoC 5.
Change required to prevent the component from impacting
unrelated analog signals when stopped, when used with
PSoC 5.
Mixer Response GUI implementation
To guide the user to an understanding of Mixer
performance.
Added PSoC 5 characterization data to
datasheet
1.60
Removed VDDA parameter from
component customizer
Document Number: 001-79357 Rev. *A
VDDA setting in the component is redundant and
unnecessary for multiple components. The parameter was
removed and the component queries the global setting for
minimum VDDA in the DWR and automatically enables the
pump when necessary.
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PSoC® Creator™ Component Datasheet
Mixer
Version
Description of Changes
Reason for Changes / Impact
Added a GUI Configuration Editor
Previous configuration window did not provide enough
information for ease of use.
LO - local oscillator is enabled correctly
The local oscillator was not being enabled correctly in
previous versions of the component.
Added characterization data to
datasheet
Minor datasheet edits and updates
1.50
Added Sleep/Wakeup and Init/Enable
APIs.
To support low power modes, as well as to provide
common interfaces to separate control of initialization and
enabling of most components.
Updated Symbol and Configure dialog.
To comply with corporate standards.
© Cypress Semiconductor Corporation, 2012-2015. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the
use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to
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Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in lifesupport systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application
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Use may be limited by and subject to the applicable Cypress software license agreement.
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Document Number: 001-79357 Rev. *A
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