Chebyshev-based cascaded single-stage distributed amplifier design for enhanced gain and bandwidth control

Purpose This paper aims to enhance the performance of the cascaded single-stage distributed amplifier (CSSDA) by proposing a novel architecture that simultaneously improves gain, bandwidth and ripple rate control. The objective is to address the trade-off between gain enhancement and bandwidth reduction typically encountered in distributed amplifiers (DAs). Design/methodology/approach A new structure, referred to as the Chebyshev CSSDA (Ccssda), is introduced. In this architecture, the input and output artificial transmission lines are left open-circuited, which doubles the gate-source voltage and increases the output current, resulting in a 12-dB gain improvement at low frequencies. However, this introduces impedance mismatches that affect bandwidth. To overcome this, the amplifier’s transfer function is analytically derived and approximated using Chebyshev polynomials, enabling ripple control and gain flattening. A cascode configuration is also integrated to mitigate nonideal transistor behavior. Findings The proposed Ccssda design achieves a significant gain enhancement of approximately 12 dB compared to the conventional CSSDA. Moreover, the Chebyshev-based approximation ensures gain uniformity and bandwidth stability up to the desired cutoff frequency. Simulation results confirm the effectiveness of the method and demonstrate the feasibility of ripple rate control through impedance tuning. Originality/value The novelty of this work lies in the combination of an open-circuited artificial line structure with a Chebyshev approximation method to improve amplifier performance. The proposed methodology offers flexibility and can be applied to any transistor technology using normalized design parameters. This work contributes to the development of high-performance DAs for broadband RF and mm-wave applications.