No abstract

signed RLC network will bring side effects, i.e., a worse S 22 around the cut-off frequency, as shown in Figure 6. A trade-off in design should be made between a wider bandwidth and a decent stability.To further demonstrate the amplifier bandwidth improvement from series RLC network, a common-emitter amplifier and a common-collector followed by a common-emitter amplifier are designed for a complete comparison. The measured S 21 parameters are plotted in Figure 7. For the sake of fair comparison, all amplifiers are biased at the same collector current. Input and output ports are terminated with 50 ⍀. From Figure 7, a much wider bandwidth is achieved in amplifier with the RLC network. CONCLUSIONSA bandwidth improvement network incorporated with a gain compensation technique is proposed for HBT amplifiers. The network consists of a small value of inductor at base of Q3, in series with a decoupling capacitance and a resistance to improve high frequency stability. The network cannot only be implemented in a common-collector following by a cascode amplifier, but also in a traveling wave matching (TWM) amplifier, a distributed amplifier (DA), and a matrix amplifier (MA) [5][6][7][8][9]. The network has been demonstrated to improve the bandwidths of various amplifiers.