[Legacy Report] IEEE-EDS seminar by Imon Mondal on "Synthesis and Application of a Wideband Tunable True-Time-Delay Architecture using a Variable Order All-Pass Filter"

#EDS #Kanpur

An all-pass filter architecture that can be generalized to high orders, and can be realized using active circuits is proposed. Using this, a compact true-time-delay element with a widely tunable delay and a large delay-bandwidth product is demonstrated. This is useful for beamforming and equalization in the lower GHz range where the use of LC or transmission line based solutions to realize large delays is infeasible. A test chip fabricated in 0.13 μm CMOS process demonstrates a delay tuning range of 250 ps – 1.7 ns, over a bandwidth of 2 GHz, while maintaining a magnitude deviation of ±0.7 dB. The filter achieves a delay-bandwidth product of 3.4 and a delay per unit area of 5.8 ns/mm². Computed radiation pattern with four antennas spaced λ_fmax/2 apart shows ±90^o beam steering off broadside.

Exploiting the feasibility of large delay bandwidth product of this architecture, a high order all-pass filter has been used to demonstrate true-time expansion and compression of narrow, wideband pulses. It is based on storing the input pulse as state variables in a continuous-time filter whose delay exceeds the pulse duration, and, once the pulse is completely “inside” the filter, reducing or increasing its bandwidth. Expansion and compression enable processing and generation of high speed pulses using low speed circuits. The proposed method is amenable towards a monolithic integration unlike the photonic or microwave implementations based on dispersive media. Pulse expansion and compression by factors of 1.8× and 1.7× respectively are demonstrated in a 0.13 μm CMOS process.

• Date: 10 Jul 2017
• Time: 10:30 AM UTC to 12:30 PM UTC
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• Kanpur, Uttar Pradesh
• India

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