Bandwidth enhancement technique for bipolar single stage distributed amplifier design

Abstract

Abstract-This work reports a novel approach to extending the bandwidth of single stage distributed amplifiers (SSDAs). The three-stepped technique involves scaling down the inductance on the input artificial transmission line (ATL); creating a high frequency resonance peak by the addition of shunt capacitance on the input ATL; and compensating for the resulting increased reflection with adapted negative resistance attenuation compensation techniques. Compared with the inductive-peaked cascode technique applied in the SSDA which currently has the highest reported bandwidth, simulation results, based on full foundry transistor models, predict up to 30% improvement in gainbandwidth (GBW) performance for the same active device at the same bias. In addition, the reduction in the length of the input ATL effectively reduces transmission line losses, thereby improving the overall gain performance.

InP DHBT Single-Stage and Multiplicative Distributed Amplifiers for Ultra- Wideband Amplification

“…2 [11], [20], [22], [23]. This complex input nature of HBTs generally results in worse termination mismatch and higher input reflection with additional stages [9], [24]. Furthermore, the gentle frequency response roll-off of the single stage lowpass filters that make up the input and output ATLs of the SSDA is easily compensated for, using available attenuation compensation and bandwidth extension techniques, such as those presented in [24]- [27].…”

“…N = 1), G DA is limited by g m , which is quite low for high f T devices. The issue of limited gain has been addressed through multiplicative DA topologies -formed from cascading or arranging SSDAs in a matrix [9], [10], [16], [19], [24], [28]- [30].…”

“…The cascode configuration is favoured for the high input-output isolation it offers, as well as the high output impedance which advantageously reduces the loading on the output transmission line of the DA [29], [46]. To improve bandwidth performance, the input transmission line is scaled down by a factor ζ ≈ 0.5 and peaked by a shunt capacitance C peak = 1 2 C π , where C π is the input (baseemitter junction) capacitance of the active device [24], creating a similar effect to the application of a radial stub [47]. The loss compensation technique described in [24] was employed, involving the addition of peaking inductances L cc and L ce to the cascode gain cell, with L cb added to maintain stability [24], [25].…”

Derivation of the Equivalent Input Noise of Multiplicative Distributed Amplifiers for Wideband Optical Receiver Applications

“…and the EINCSD (i neq ) is obtained by dividing v nout given by (14), by the amplifier transimpedance A tz given by (5). The input noise current contributions due to v o1 , v o2 and v o3 may also be individually determined by dividing each by A tz .…”