A Delay Filter for an IR-UWB Front-End

Abstract

A continuous-time analog delay is designed as a requirement for the autocorrelation function in the Quadrature Downconversion Autocorrelation Receiver (QDAR) [1]. An eightorder Pade approximation of its transfer function is selected to implement this delay. Subsequently, the orthonormal form [1] is adopted, which is intrinsically semi-optimized for dynamic range, has low sensitivity to component mismatch, high sparsity and whose coefficients can be physically implemented. Each coefficient in the state-space description of the orthonormal ladder filter is implemented at circuit level using a novel 2-stage gm cell employing negative feedback. Simulation results in IBM's Bi-CMOS 0.12 pm technology show that this delay filter requires a total current of 70 mA at a 1.6 V power supply. The 1-dB compression point of the delay is at 565 mV and the SNR is 47.5 dB. On performing a Monte Carlo simulation it becomes evident that the response of the frequency selective analog delay does not suffer drastically from neither process variations nor component mismatch.

A Novel Differential Chaos Shift Keying Modulation Scheme

“…The analog receiver configurations can remarkably reduce the power consumption, but the ultra-wideband RF delay lines required are extremely difficult to implement in CMOS [Bagga et al, 2005;Stralen et al, 2002]. For instance, a delay of 20 ns is realized with a 20 foot coaxial cable in [Stralen et al, 2002].…”

Ultra-Wideband Radio: Unconventional Circuit Solutions for Unconventional Communication

“…As the interferers may be stronger than the UWB signal their presence after downconversion and filtering may still deteriorate the outcome of the autocorrelation function. Hence, to further reduce the influence of the narrowband interferers, frequency selectivity is introduced in the delay element [5]. Assuming that the incoming waveform at the receiver, x(t), is a Morlet given by, (4) where α is the center frequency and τ is the time instant at which the Morlet waveform is centered, the impulse response, h(t), of the delay filter is chosen to match the incoming signal (i.e.…”

“…From comparing (4) with (5), one sees the distinct resemblance between the convolved waveform and the incoming Morlet signal. The design procedure of the filter based time delay is the same as described in III.…”

“…analog delay [4] and a filter based delay line [5] have been designed. For a time delay of 0.55ns, simulation results in CMOS 0.13µm technology show that the quantized analog delay requires a total current of 36.7mA at a 1.6V power supply.…”