7 to 20 MHz Intermediate frequency amplifier

The device is a dual Intermediate-frequency amplifier (IFA) which consists of 4-stage amplifier with tunable gain, an input linear buffer for analog output and an analog-digital converter for digital output and a detector of output level.
The amplifier has differential inputs and outputs, and consists of 4 stages. Gain is sequentially reduced from the last stage to the first stage. This method allows to keep a low noise figure in wide gain range.
The amplifier can operate in the following modes:
- linear output with automatic gain control (AGC);
- digital output with AGC for analog signal;
- digital output with AGC for digital signal.
In the analog output mode the circuit retains a low output offset voltage and controls the gain so that the magnitude of the differential output signal is 200 mV peak-to-peak. DC offset compensation system operates both at an amplifier output signal and at a buffer output signal.
The block is fabricated on SMIC CMOS 0.18 um technology.