Abstract
This paper presents a methodology to design a wideband radio frequency variable gain amplifier (RF-VGA) in a low-cost SiGe BiCMOS 0.35 μm process. The circuit uses two Class A amplifiers based on second-generation controlled current conveyors (CCCII). The main feature of this circuit is the wideband input match along with a reduced NF (5.5–9.6 dB) and, to the authors’ knowledge, the lowest die footprint reported (62 × 44 μm2 area). The implementation of the RF-VGA based on CCCII allows a wideband input match without the need of passive elements. Due to the nature of the circuit, when the gain is increased, the power consumption is reduced. The architecture is suitable for designing wideband, low-power, and low-noise amplifiers. The proposed design achieves a tunable gain of 6.7–18 dB and a power consumption of 1.7 mA with a ±1.5 V DC supply. At maximum gain, the proposed RF-VGA covers from DC up to 1 GHz and can find application in software design radios (SDRs), the low frequency medical implant communication system (MICS) or industrial, scientific, and medical (ISM) bands.
Highlights
In radio frequency integrated circuits, the design of wideband amplifiers has been intensively discussed over the past few decades [1]
At system level, when implementing a wideband analog RF front-end, the most popular scheme includes a wideband low noise amplifier (LNA) followed by a variable gain amplifier (VGA). This maximizes the dynamic range of the upcoming stages and prevents the saturation of the receiver if a high-powered signal is received [17]
The linearity of the proposed radio frequency variable gain amplifier (RF-VGA) was evaluated by measuring the input 1-dB compression point (P1dB ) using a test tone of 666 MHz
Summary
In radio frequency integrated circuits, the design of wideband amplifiers has been intensively discussed over the past few decades [1]. The most widely used wideband amplifier architecture is the distributed amplifier, which requires high power consumption and a large area due to the considerable number of stages and the extensive use of inductors [2,3,4]. To reduce the area constraints, some authors have proposed the use of common-base or common-gate wideband amplifiers [14,15,16] These topologies take advantage of the fact that, in such configurations, it is possible to obtain a broadband input impedance equal to 50 Ω by properly biasing the transistor. At system level, when implementing a wideband analog RF front-end, the most popular scheme includes a wideband low noise amplifier (LNA) followed by a variable gain amplifier (VGA) This maximizes the dynamic range of the upcoming stages and prevents the saturation of the receiver if a high-powered signal is received [17].
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