CLC5506 Gain Trim Amplifier (GTA) General Description Features The CLC5506 is a low-noise amplifier with programmable gain for use in cellular base stations, WLL, radar and RF/IF subsystems where gain-control is required to increase the dynamic range. The CLC5506 allows designers to compensate for manufacturing component tolerances and temperature variations in receiver front ends. Maximum amplifier gain is set at 26dB . A three-line MICROWIRE serial interface allows 16dB of attenuation from the max gain setting in precise 0.25dB steps. The CLC5506 uses a differential input and output, allowing large output swings on a single 5V rail. The differential output is well suited for impedance matching networks driving SAW filters or directly driving differential input analog to digital converters (ADC). The differential output also makes it possible to drive transformers allowing designers the ability to match a wide variety of transmission lines. The output amplifier has excellent output drive with low distortion. Digital control of the CLC5506 is accomplished using MICROWIRE Interface. Data Out and a Load Enable are incorporated so that more than one CLC5506/channel may be programmed per system. The CLC5506 maintains a 600MHz performance bandwidth over its entire gain and attenuation range from +10dB to +26dB. Gain control is divided into 64 equal steps of 0.25dB and is dB-linear. Output drive and distortion performance are excellent; In a 50Ω system, the third-order output intercept point is +22dBm at nominal gain of 18dB at 25˚C. The CLC5506 operates over the industrial temperature range of −40˚C to +85˚C. n n n n n n n n n n n n 600MHz bandwidth 26dB maximum gain @ 150MHz 16dB gain control range Attenuation step size: 0.25dB 4.8dB noise figure @ 26dB +22dBm output IP3 @ 18dB gain Digital ″dB Linear″ gain control Supply voltage: 5V Supply current: 75mA Supply shutdown: 35µA Package: SOIC-14 Typical at 25˚C Applications n n n n n n n n n Cellular base-stations Base station repeater Wireless Local Loop Radar Receivers IF amplifiers Digital IF receiver Software radio Satellite communications Frequency Response vs. Gain Setting DS101050-1 MICROWIRE™ © 1999 National Semiconductor Corporation DS101050 www.national.com CLC5506Gain Trim Amplifier (GTA) September 1999 Typical Application DS101050-2 www.national.com 2 Connection Diagram CLC5506 Pin Diagram DS101050-3 Top View Pin # 1 Pin Name NC Description No connection 2 GNDA Analog ground 3 In+ Positive differential input 4 In− Negative differential input 5 LE MICROWIRE load enable input. High impedance CMOS input with Schmitt trigger 6 Clock MICROWIRE clock input. High impedance CMOS input with Schmitt trigger. Data is clocked in on the rising edge of clock. 7 Data In MICROWIRE data input. High impedance CMOS input with Schmitt trigger. Binary serial data. Data entered Power Down first. 8 Data Out MICROWIRE data output. High impedance CMOS input with Schmitt trigger. 9 GNDD Digital ground 10 VCCD Digital supply voltage 11 Out− Negative differential Output 12 Out+ Positive differential output 13 GNDA Analog ground 14 VCCA Analog supply voltage Ordering Information Package SO-14 Temperature Range −40˚C to +85˚C CLC5506IM CLC5506IMX Transport Media NSC Drawing Rails M14a 2.5k Units Tape and Reel CLC5506PCASM Fully loaded evaluation board 3 www.national.com Absolute Maximum Ratings (Note 1) Storage temperature range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Junction temperature 250V Differential input voltage Supply voltage (pins 10 and 14) +/−1V Supply voltage −0.3V to VCC Analog input voltage −0.3V to VCC Output short circuit duration 5V +/− 10% Ambient temperature range −0.3 to +6V Digital input voltage < 200mV Operating Ratings (Note 1) 2.5KV Machine model 155˚C Differential voltage between any two inputs ESD tolerance(Note 2) Human body model −65˚C to 150˚C −40˚C to +85˚C Junction Temperature Range −40˚C to +150˚C Package thermal resistance, θJA 127˚C/W Infinite Lead temperature (soldering, 10 sec) +300˚C Electrical Characteristics These conditions apply unless otherwise specified: T −30dBm (Note 6),(Note 7). Symbol Parameter J = 25˚C, VCCA = VCCD = +5V: Gain = 25.75dB, RLdiff = 100Ω, Pin = Typ (Note 3) Conditions Limit (Note 4) Units Analog I/O Frequency Response/Distortion/Noise upper −3dB bandwidth All Gain Codes upper −1dB bandwidth All Gain Codes 600 gain flatness in any 1MHz band 10MHz < f < 600MHz, All Gain Codes MHz 400 MHz 0.003 dB group delay 50MHz < f < 600MHz 1.5 nsec group delay ripple 50MHz < f < 600MHz 18dB Gain, f = 110MHz 0.5 nsec 22 dBm noise figure Gain = 25.75dB, (Note 6) Gain = 18dB, (Note 6) Gain = 10dB, (Note 6) 4.8 5.7 7.0 dB dB dB 1dB output compression point 150MHz 4.0 dBm 2nd harmonic distortion Pin = −30 dBm, fc = 200MHz @ Gain = 25.75dB @ Gain = 10dB Pin = −30 dBm, fc = 200MHz @ Gain = 25.75dB @ Gain = 10dB 46 46 dBc dBc 49 56 dBc dBc 45 dB output third order intercept point 3rd harmonic distortion Input/Output Isolation power down mode Full frequency band Gain Parameters: (Note 5) maximum gain Full temperature range 25.75 dB minimum gain Full temperature range 10 dB gain step size Full temperature range 0.25 dB accuracy of gain setting @ 25˚C ± 0.05 dB gain variation over temperature Full temperature range ± 0.5 dB input resistance Differential 200 Ω input capacitance Differential 0.5 pF Input/Output Characteristics: www.national.com 4 Electrical Characteristics (Continued) These conditions apply unless otherwise specified: T −30dBm (Note 6),(Note 7). Symbol Parameter J = 25˚C, VCCA = VCCD = +5V: Gain = 25.75dB, RLdiff = 100Ω, Pin = Typ (Note 3) Conditions Limit (Note 4) Units Input/Output Characteristics: output resistance Differential 5K Ω output capacitance Differential 0.5 pF clock speed Maximum 1 MHz data to clock setup time, TCS Minimum 50 nsec data to clock hold time, TCH Minimum 10 nsec clock pulse width high, TCWH Minimum 50 nsec clock pulse width low, TCWL Minimum 50 nsec clock to load enable setup time, TES Minimum 50 nsec high level input voltage 0.7 VCCD V low level input voltage 0.3 VCCD V ± 1.0 µA Logic I/O High level input current low level input current high level output voltage Isource = 0.5mA low level output voltage Isink = 0.5mA ± 1.0 µA VCCD −0.8 V 0.4 V DC Characteristics: Supply current 75 95 mA Supply current in power down mode 35 100 µA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: Human body model, 1.5kΩ in series with 100pF. Machine model, 200Ω in series with 100pF. Note 3: Typical values represent the most likely parametric norm. Note 4: All limits are guaranteed by testing or statistical analysis, unless otherwise noted. Note 5: AC test performed at 400MHz unless otherwise noted. Note 6: Refer to test circuit schematic, loss of transformers is excluded from the measurement. Note 7: Refer to test circuit schematic to see the definition of RLdiff. 5 www.national.com Typical Performance Characteristics (VCCA = VCCD = +5V, RLdiff = 100Ω, TA = 25˚C, unless other- wise specified.) Frequency Response vs. Gain Setting (0.25dB/step) Gain vs. Input Code DS101050-5 DS101050-4 Gain Error vs. Input Code Output 3rd Order Intercept vs. Input Code DS101050-6 DS101050-7 Input 3rd Order Intercept vs. Input Code Noise Figure vs. Input Code DS101050-8 DS101050-9 Gain Change Over Temperature vs. Frequency Gain Change Over Temperature vs. Frequency DS101050-10 www.national.com DS101050-11 6 Typical Performance Characteristics (VCCA = VCCD = +5V, RLdiff = 100Ω, TA = 25˚C, unless otherwise specified.)) (Continued) Gain Change Over Temperature vs. Frequency NF Change Over Temperature vs. Frequency DS101050-12 DS101050-13 NF Change Over Temperature vs. Frequency NF Change Over Temperature vs. Frequency DS101050-14 DS101050-15 P1dB vs. Gain Setting DS101050-16 7 www.national.com DS101050-17 FIGURE 1. CLC5506 Functional Block Diagram APPLICATION NOTE fore being used to set the gain of the input signal. The ″Linear to Exponential″ block and the ″Temperature Compensation″ blocks work in conjunction to achieve gain stability over the temperature range. Finally, the output stage consists of a variable gain cell with open Collector output. This variable gain cell sets the signal channel gain in accordance with the value of the digital code. Gain Control The CLC5506 minimum gain is at 10dB nominal. There are a total of 64 distinct gain control codes possible (serial data input through Data In pin) at 0.25dB/code resulting in a maximum nominal gain of 25.75dB. Therefore, the overall gain can be written as: Gain (dB) = 10dB + Ncode * 0.25 (dB/code) Description Figure 1 above shows the CLC5506 functional block diagram overview. The LNA (Low Noise Amplifier) is responsible for maintaining a nominal input impedance of 200Ω with minimum noise contribution and some finite and fixed amount of gain (∼4). Exceptional Noise Figure (NF) performance of 4.8dB ( @ Gain = 25.75dB) is achieved by utilizing an active impedance matching circuit technique which overcomes the inevitable 3dB NF penalty when using passive shunt matching. The LNA stage is immediately followed by a transconductance stage (Gm) which then converts the LNA’s voltage output into a differential current output with fixed gain. The 6-bit D/A converter, which processes the digital code read into the device using the MICROWIRE interface, consists of a 6-bit R2R ladder. In order to achieve true ″Linear in dB″ gain control at the output, the D/A converter output is processed by a ″Linear to Exponential″ converter block be- where Ncode refers to the decimal equivalent of the 6-bit gain control code. TABLE 1. Gain Typical Gain Setting (dB) 0 10 1 10.25 2 10.5 *** *** K 10 + 0.25 *K *** *** 62 25.50 63 25.75 Maximum Gain Setting Power Down The CLC5506 is able to go to a Power Down mode in order to minimize its power consumption to a fraction of its nominal value. The Power Down mode is activated through the MICROWIRE interface by clocking in a ″1″ into the Power Down shift register prior to allowing LE (pin 5) to go high. Refer to Figure 2 and Figure 3 for more information. www.national.com Note Minimum Gain Setting In Power Down mode, the CLC5506 sinks less than 35µA. The CLC5506 will wake up to the requested gain level specified by Data In through the MICROWIRE interface. When VCC is first applied, the device is configured such that it would always ″wake up″ with a nominal gain of 17.75dB (Ncode = 3). 8 APPLICATION NOTE With LE low, each successive positive transition of Clock will read the value of the Data In into a series of 8 single bit shift registers. In order to load all 8 registers, 8 Clock transitions are required after which, when LE is allowed to go High, the new values in the shift registers are latched to determine the device gain setting (or Power Down state). New data can be shifted into the device with the present gain setting not affected as long as LE is held low. Data from the last register in the chain is clocked out on Data Out pin on the negative transitions of Clock as shown in Figure 3. This enables several MICROWIRE Interface devices to be daisy chained and controlled from a single bus master. (Continued) MICROWIRE™ Interface Data In along with the Clock, LE, and Data Out, is used for the following purposes: Setting the 6-bit gain control code Putting the device into a Power Up/Down mode to minimize power consumption Daisy chain several CLC5506 or other MICROWIRE Interface devices through the Data Out pin The MICROWIRE interface timing diagram along with the bit assignment of all 8 bits is shown in Figure 2. The interface is active only when LE (pin 5) is low; otherwise, the interface is inactive (Clock and Data In are ignored) and the CLC5506 gain is the current content of the 6 bits already read into the device. The maximum clock frequency (Clock pin) is 1MHz. DS101050-18 Note: 1. Data is clocked in on the rising edge of Clock. 2. Power Down bit is the first data to enter the CLC5506. FIGURE 2. MICROWIRE Interface Timing Diagram DS101050-19 FIGURE 3. MICROWIRE Interface Serial Data Out Timing 9 www.national.com APPLICATION NOTE puts is used to set the output resistance of CLC5506. Wideband output matching to an unbalanced 50Ω load can be achieved by using a 1:n balun. A 1:4 impedance ratio balun is used when a 200Ω external resistor is used in a 50Ω system. Although the CLC5506 can be used as a single-ended device by grounding one of the inputs through a capacitor, the noise figure would be severely degraded by 6dB. (Continued) Differential Input and Output Considerations The CLC5506 typical application requires DC blocking capacitors for both inputs and outputs to main internal DC biasing points. The input impedance between the differential inputs (IN+, IN-) is 200Ω//0.5pF. Since the 0.5pF capacitance can be neglected in the VHF band, a 1:4 impedance ratio balun can be used to transform a 50Ω source to the 200Ω differential inputs of CLC5506 for wide band design. The CLC5506 can also directly interface to balanced devices, like SAW filters and ADCs. Narrowband design example with ADC CLC5956 and SAW filter is provided below. The component values of matching inductors and capacitors depend on the actual input/output impedance of the SAW filter, ADC, PWB properties, layout and frequency band. The CLC5506 has a pair of open collector differential outputs (OUT+, OUT-). DC biasing is achieved through an RF inductor. The RF inductor acts as a choke to block RF leakage and interference. An external resistor across the differential out- DS101050-20 FIGURE 4. Narrow band design example with balanced SAW filter and ADC CLC5506 Evaluation Board A proper printed circuit layout is essential for achieving high frequency performance. To expedite evaluation, an assembled and tested evaluation kit CLC5506PCASM is available for sale. See application note AN-1138 for technical details of evaluation kit. Order information and application note is available on the Web at http://www.national.com www.national.com 10 DS101050-21 CLC5506 Test Circuit Schematic 11 www.national.com CLC5506Gain Trim Amplifier (GTA) Physical Dimensions inches (millimeters) unless otherwise noted 14-Pin Small Outline NSC Package Number M14A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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