SA612 RF Mixer IC: Pin Diagram, Circuit & Uses
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SA612, also known as NE602 in compatible implementations, is a low power double balanced RF mixer and oscillator IC used for frequency conversion in communication circuits. It combines a mixer with an on chip oscillator section and is commonly used in receiver front ends, frequency converters, RF experiments, IF stages, and other low power communication applications.
Key features of SA612
- Operating Frequency: Operates with signal frequencies up to 500 MHz and local oscillator (LO) frequencies up to 200 MHz.
- High Performance: Provides an excellent conversion gain of 14 dB (or more) and a low Noise Figure (typically below 6 dB) at 45 MHz.
- Low Power Consumption: Excellent for battery-operated equipment, drawing only 2.4 mA (typical) of supply current.
- Oscillator Flexibility: The on-board oscillator can be configured for crystal operation, tuned tank (L/C) operation, or acting as a buffer for an external Local Oscillator (LO).
- Low Radiated Energy: Minimizes radiated energy levels within communication networking systems.
- Low External Parts Count: Designed to easily interface with external crystal or ceramic filters.
SA612 Pin Diagram
Pin Details (8-Lead SO Package)
| Pin Number | Symbol | Description |
|---|---|---|
| 1 | IN_A | RF Input A (Differential input stage) |
| 2 | IN_B | RF Input B (Differential input stage) |
| 3 | GND | Ground |
| 4 | OUT_A | Mixer Output A |
| 5 | OUT_B | Mixer Output B |
| 6 | OSC_B | Oscillator Input (Base of the internal oscillator transistor) |
| 7 | OSC_E | Oscillator Output (Emitter of the internal oscillator transistor) |
| 8 | VCC | Supply Voltage (4.5V to 8.0V range) |
Example Use Case : 45 MHz to 455 kHz Down-Conversion in a Cordless/Cellular Radio
In this use case, SA612A is used as the second Intermediate Frequency (IF) mixer in a cellular telephone receiver. In this circuit design, 45 MHz RF signal is fed into the differential input pins (IN_A/IN_B). The output beat frequency of 455 kHz IF signal (OUT_A/OUT_B) is fed directly into a 455 kHz ceramic filter (e.g. SFG455A3) before moving on to a demodulator IC (e.g. SA614A). SA612A can achieve excellent sensitivity; capable of receiving exceptionally faint –119 dBm signals with a solid 12 dB Signal to Noise ratio (SNR) while draining very little battery power.
Applications of SA612
- Cordless telephones and Cellular radios (mixer/oscillator stage)
- Portable radios and VHF transceivers
- RF data links
- Communications receivers
- Broadband Local Area Networks (LANs)
- HF and VHF frequency conversion
- Sonobuoys
Summary
SA612 combines RF mixing and oscillator functions in a compact, low power IC, simplifying frequency conversion circuits. It is useful for receiver front ends, IF stages, RF experimentation, and other communication applications.