A 45 dB variable gain low noise MMIC amplifier

Abstract

-A variable gain amplifier operating at 2.5 GHz based on Single Ended topology has been designed and characterized. Three such stages were cascaded preceded by a single stage LNA. A source follower is used at the output as an active load matching. Overall dynamic gain variation is 45 dB with a maximum gain of 47 dB. The -3 dB bandwidth is 0.800 GHz. A minimum noise figure of 0.81 dB is obtained in the highest gain mode. Maximum value of 1 dB compression at the output is -7.2 dBm and the corresponding third order intercept point is +5.3 dBm. Consumed DC power 285 mW and is immune to gain variation. The circuit is implemented with GaAs pHEMT technology. The combined area occupied by the multistage low noise VGA and the single ended VGA is 3.5 mm X 3 mm.

Monolithically integrated high performance digital variable gain amplifiers

“…In order to maintain RF/IF power to an optimum level with respect to the large signal amplitude variation in the wireless system, wide dynamic range in the VGA design is required, as well as high output third order intercept point (OIP3) and minimal noise figure [1]- [2]. In addition to the traditional analog VGAs with varying DC voltage to control the gain, digitally-controlled VGA (DVGA) can also achieve the functions of analog VGA.…”

A variable-gain single-bit ultra-wideband quantizer for baseband receiver front-end

“…With the gradual downscaling of existing technologies, development of systems in microwave frequency becomes more promising for high data-rate transmission [1]. For its low cost, low power, high data-rate and high spectrum efficiency, UWB systems have emerged as a major technology for high data service in short-range wireless communication systems.…”