RX3361 Low Power IF Receiver IC Advance Informaation Princeton Technology Corp. reserves the right to change the product described in this datasheet. All information cont-tained in this datasheet is subject to change without prior notice. Princeton Technology Corp. assumes no responsibility for the use of any circuits shown in this datasheet.rates a quadrature FM demodulator, on-chip audio filter, and a squelch/mute circuit. Description The RX3361 is a low power IF receiver IC which is fully compatible with the Motorola MC3361C IC and is suitable for use as the second IF downconverter in double conversion receiver systems. The RX3361 is well-suited for wireless FM applications and incorporates a quadrature FM demodulator, on-chip audio filter, and a squelch/mute circuit. Features Supply voltage range: 2 to 6 V Built-in crystal oscillator for mixer local oscillator Mixer input frequency: 10 — 50 MHz Quadrature detector On-chip audio filter Audio output SOP150-16L package Block Diagram 16 15 MIX IN GND 14 MUTE 13 SCAN CTL 12 SQU IN 11 FLT OUT 10 FLT IN 9 AUD OUT SQUELCH CIRCUIT IFAMP OSCILLATOR 1 XSC0 2 XSC1 QUAD DETECTOR MIXER AUDIO AMP AUDIO BPF AMP 3 MIX OUT 4 VCC 5 LMTIN 6 DCP0 Page 1 For:Natertech 7 DCP1 8 QUAD July 2005 RX3361 Pin Descriptions Number Name Description 1 XSC0 Oscillator input (base) 2 XSC1 Oscillator output (emitter) 3 MIXOUT 4 VCC 5 LMTIN IF amplifier input (1.8 KΩ input impedance) 6 DCP0 IF amplifier de-coupling capacitor connection 7 DCP1 IF amplifier de-coupling capacitor connection 8 QUAD Quadrature FM demodulator input 9 AUDOUT Quadrature FM demodulator output 10 FLTIN Audio bandpass filter input 11 FLTOUT Audio bandpass filter output 12 SQUIN 13 SCANCTL Scan control output for LO. Output is high when squelch circut input level is low. 14 MUTE Mute output. Impedance to ground is low when squelch circuit input level is low. 15 GND 16 MIXIN Mixer output (1.8 KΩ output impedance) Nominal 4 V supply Squelch circuit input Ground Mixer input (3.3 KΩ input impedance) Page 2 For:Natertech July 2005 RX3361 Absolute Maximum Ratings VSS = 0 V Parameter Symbol Rating Unit Supply voltage VCC VSS – 0.3 to VSS + 8.0 V Operating temperature range TOPR –30 to 70 °C Storage temperature range TSTG –65 to 150 °C Soldering temperature range TSLD 255 °C Soldering time range tSLD 10 s Recommended Operating Conditions VSS = 0 V Parameter Symbol Supply voltage range VCC1 MIXIN input frequency fMIXIN Operating temperature TA Value min. typ. max. 2 4 6 10.7 –30 25 Page 3 For:Natertech Unit V MHz 70 °C July 2005 RX3361 Electrical Characteristics (VCC = 4.0 V, VSS = 0 V, TA = 25 °C, fo=10.7 MHz, unless otherwise noted) Parameter Symbol Condition Icc,unm Icc,mut V(pin12) = 1 V V(pin12) = 0 V Vaud On pin 9 with 10 mV rms in. Vlim3dB Total Harmonic Distortion Recovered Output Voltage Quiescent current consumption Unmuted Muted Value min. typ. max. 2.8 4.2 Unit mA 170 210 mVrms On pin 16 2.6 6 µV THD On pin 9 0.86 Vrec On pin 9 Zdet,out On pin 9 Filter Amplifier Gain Gfilt On pin 11, with 10 KHz 0.3 mV rms signal input to pin 10. Filter Amplifier dc Output voltage Vfilt On Pin 11, measured with no audio input. Mute pin resistance Unmuted Muted Runm Rmut Audio output voltage Input Limiting Voltage 130 60 190 % 350 mVrms 450 Ω 40 50 dB 0.5 0.7 0.9 V From Pin 14 to ground. V(pin12) = 1 V V(pin12) = 0 V 30 11 50 1 Ω ΜΩ VSC,unm VSC,mut Measured on pin 13. V(pin12) = 1 V V(pin12) = 0 V 0 3.9 0.4 V 3.0 Squelch Circuit Hysteresis Vhys Referred to pin 12 45 100 mV Mixer Conversion Gain Gmix From pin 16 to pin 3 28 dB Mixer Input Resistance Rmix,in On pin 16 3.3 KΩ Mixer Input Capacitance Cmix,in On pin 16 9.0 pF Audio output impedance Scan control output level Unmuted Muted Page 4 For:Natertech July 2005 RX3361 Functional Description The RX3361 IF receiver IC incorporates a mixer, crystal-based local oscillator, IF amplifier, quadrature FM demodulator, audio filter, and a squelch circuit and is capable of demodulating FM input signals. Mixer The mixer provides frequency downconversion from the 1st IF input on pin 16 down to the 455 KHz 2nd IF output on pin 3. The external 2nd IF filter should be chosen so that the specified output impedance on the mixer output port is an acceptable termination for the filter. Crystal Oscillator A single dcdc coupled transistor is available as a two port gain element (pins 1 & 2) to implement a crystal oscillator. The device is biased on-chip to a constant dc current. IF Amplifier The IF Limiter amplifies and limits the pin 5 input from the external 2nd IF filter. The output is a square wave that drives the following demodulator stage. Two off-chip decoupling capacitors to Vcc are required on pins 6 & 7 to remove dc content from the limiter input. FM Demodulator The demodulator provides an audio output generated by multiplying the input IF from the limiter with a quadrature version of the input. The quadrature version is generated by the combination of an on-chip 10pF series capacitor with an off-chip shunt LCR resonator connected between pin 8 and Vcc. Biasing for the input transistor on pin 8 comes from the off-chip resonator. The shape of the demodulator S-curve is determined by the shunt resistance on this LCR resonator. An off-chip RC low pass filter should be used on pin 9 for removal of the 2nd IF components. Filter Amplifier The filter amplifier provides an inverting gain element between pins 10 & 11 for the implementation of an audio filter. Typically, a bandpass Delyiannis-Friend active filter is built by adding externally at least two resistors and two capacitors to this amplifier. An external dc path must be provided through the feedback network across these pins to set the dc operating point. The design equations are as follows: R2 R 1 = -------2 Ao R1 ⋅ R2 ⎞ 1 R 2 = -------------2 ⋅ ⎛⎝ ---------------⎠ R 1 – R2 (2Q) Q R 3 = --------------------π ( fo ⋅ C ) where: fo is the desired center frequency, Q is the quality factor, Ao is the voltage gain at band cen- Page 5 For:Natertech July 2005 RX3361 ter, R2 is the feedback resistance, C is the value for both capacitors, R1 the series input resistance and R2 the shunt resistance. Pin 9 R1 C C R2 Pin R3 10 - Pin 11 Squelch Circuit The squelch circuit provides a means of quieting the audio output when the squelch in signal (pin 12) is lower than the threshold voltage. This is achieved by dropping the impedance on the mute output (pin 14), which typically is connected to the audio output. In addition a scan control output (pin 13) will go high. This output can be used to signal the local oscillator of the first mixer (not included on this chip) to scan to the next frequency. The squelch input signal is provided by external rectification of the audio bandpass output. It is the responsibility of the user to determine the appropriateness of the squelch input polarity. The polarity can be selected by connecting the peak detector to the ground or Vcc side. A hysteresis voltage is built into the squelch comparator to provide immunity from residual noise and IF components emerging from the bandpass. Page 6 For:Natertech July 2005 RX3361 Application Circuit R9 R8 Vcc = 4V C11 R10 R12 R5 R7 C10 D1 C12 R4 C8 R6 R11 1st IF In C6 C9 R2 R3 Audio Out C7 Scan Ctl Out C13 16 15 14 13 12 11 10 9 MIXIN GND MUTE SCAN CTL SQU IN FLT OUT FLT IN AUD OUT HiMARK RX3361 XSC 0 XSC 1 MIX OUT VCC LMT IN DCP 0 DCP 1 QUAD 1 2 3 4 5 6 7 8 C1 LC1 F1 C3 X1 C4 C2 R1 C5 C1 68p C9 1n R1 10 KΩ R9 18 KΩ C2 220p C10 0.1µ R2 3.3 KΩ R10 1.0 KΩ C3 0.1µ C11 4.7µ R3 10 KΩ pot R11 100 KΩ C4 0.1µ C12 10µ R4 6.8 KΩ R12 51Ω C5 0.1µ C13 10n R5 3.3 KΩ X1 10.245 MHz C6 22n D1 1n4148 R6 470 KΩ C7 47n F1 CFU455D2 R7 4.7 KΩ C8 1n LC1 R8 10 KΩ Page 7 For:Natertech July 2005