AN612 Overview
AN612 is a Panasonic-manufactured IC for SSB (Single Sideband) balance modulator circuits, mainly used in CB (Citizens Band) transceivers.
Description (translated): The AN612 is a semiconductor integrated circuit designed for the balance modulator circuit of SSB-mode CB transceivers.
Features
- Low operating voltage
- High carrier suppression — the key job of a balanced modulator is to cancel out the carrier wave and pass only the sidebands; this IC does that well
- Compact 7-lead plastic SIL package (Single In-Line)
Package
7-pin SIL (Single In-Line) plastic package, with dimensions given in mm (roughly 18.5 mm tall body, 6.3 mm max width). Pins are numbered 1–7 down one edge.
What's inside (Schematic)
The equivalent circuit is a fairly dense double-balanced modulator/mixer topology:
- Q1–Q4 and diodes D1–D5 form a bias/reference network tied to pin ④ (ground) and pin ⑤
- Q9–Q12 form a cross-coupled differential pair — this is the classic Gilbert-cell-style balanced mixer core that multiplies the carrier and signal inputs
- Q13–Q16 and Q17/Q18 form the output buffer stage feeding pins ⑥ and ⑦
- Pins ① (signal in), ② and ③ (carrier in), ④ (GND), ⑤ (bias reference), ⑥/⑦ (differential output) are the functional I/O
This is essentially a double-balanced modulator (Gilbert-cell mixer) — you feed in an audio/IF signal and an RF carrier, and it outputs the double-sideband suppressed-carrier (DSB-SC) signal, which then typically goes to a crystal/mechanical filter to produce SSB.
Absolute Maximum Ratings (Ta = 25°C)
| Item | Symbol | Rating | Unit |
|---|---|---|---|
| Supply voltage | V_CC | 14.4 | V |
| Circuit voltage | V1-4 | +7 / 0 | V |
| Supply current | I_CC | 15 | mA |
| Circuit current | I5 | +1 / −2 | mA |
| Circuit current | I7 | +2 / −2 | mA |
| Power dissipation | P_D | 220 | mW |
| Operating temp | T_opr | −20 to +70 | °C |
| Storage temp | T_stg | −55 to +125 | °C |
Electrical Characteristics (Ta = 25°C, V6 = 12.0V unless noted)
| Item | Symbol | min | typ | max | Unit |
|---|---|---|---|---|---|
| Total circuit current | I_tot | 6.5 | 9.5 | 12.5 | mA |
| Zener voltage | V_ZD | — | 6.15 | — | V |
| Signal input terminal voltage | V1-4 | — | 3.1 | — | V |
| Carrier input terminal voltage | V3-4 | — | 3.4 | — | V |
| Output terminal voltage | V7-4 | — | 8.6 | — | V |
| Output voltage (balanced modulator AC), at V6=9.0V | V_O(BM) | −6 | −3 | 0 | dBm |
| Carrier suppression ratio | SC | 40 | 50 | — | dB |
The 50 dB typical carrier suppression is the headline spec — that's how cleanly it nulls out the carrier so only the sidebands come through, which is exactly what you want feeding into an SSB filter.
Test circuits
- Test Circuit 1 just powers the IC (V_CC = 12V) to measure static bias voltages/currents at each pin.
- Test Circuit 2 is the actual modulator test setup: two signal generators — SG1 at 10 kHz/170 mVrms (the "audio" signal) and SG2 at 11 MHz/50 mVrms (the "carrier") — are injected, VCC = 9V, and the output is measured on a spectrum analyzer. This is how they verify the −3 dBm typical output and 50 dB carrier suppression.
See also,
