Programmable gain amplifier design for 13.56 MHz radio receiver

Abstract

Programmable gain amplifiers are widely used nowadays in many devices such as radio receivers, communication systems, disk drives and medical equipment. A programmable gain amplifier is the key building block of an automatic gain control circuit. In an automatic gain control circuit, the gain of the receiver path can be automatically adjusted to provide a constant output signal, even though the input signal can be in a large variation. It is desirable to have a variable gain amplifier with uniform linearity performance at every gain settings and with a linear in decibels gain characteristic.

In this project, previous reported PGA design techniques, namely binary weighted switching technique-based PGA and conventional cascade PGA, were verified under Cadence environment. After that, a high dynamic range PGA with better linearity and smaller gain error was designed for 13.56 MHz Radio Receiver in GF 65 nm CMOS Technology.

For the proposed cascade PGA, differential pair with source degeneration technique was adopted with pseudo-exponential approximation. According to the simulation results, the proposed cascade PGA exhibits a -3 dB bandwidth of 57 MHz for maximum gain setting and a dB-linear range from -2.92 dB to 26.99 dB with gain errors less than ± 0.5 dB.