Hajir Hedayati

  • Citations Per Year
Learn More
This paper presents a high performance two-path wideband receiver (RX) for mobile applications. The RX uses an extra gain stage after the LNA to significantly improve the noise figure (NF). Furthermore, different RF and baseband blocker rejection techniques are proposed to significantly improve the linearity of the RX. The blockers are first rejected after(More)
This paper presents an integrated sensing system for complex dielectric spectroscopy in the 0.62-10 GHz frequency range. A capacitive sensor exposed to the material under test (MUT) shows variations in its admittance according to the complex permittivity of MUT. The sensing capacitor along with a fixed capacitor forms a voltage divider circuit and is(More)
A highly linear, efficient, two-stage power amplifier for high-data-rate wireless applications is presented. The linearity is greatly improved by adding an auxiliary amplifier to the main bipolar transistor amplifier in a feed-forward approach to cancel out the nonlinearity terms. The efficiency enhancement is achieved using a switchable biasing and a(More)
In spite of the FCC regulations, the coexistence of ultra-wideband (UWB) and narrowband (NB) systems is still an unsolved challenge. A UWB transmitter (TX) can severely degrade the performance of an IEEE 802.11a system. In this paper, a fully integrated analog impulse-radio UWB TX is presented that generates a novel UWB pulse with a tunable notch at the(More)
One of the serious challenges in Ultra Wide-band (UWB) systems is the in-band interferer system in the middle of the UWB band which affects the system performance severely. In this paper an analog in-band interference avoidance IR-UWB transmitter is presented. The fully integrated transmitter generates a novel UWB pulse with a tunable notch at the frequency(More)
A highly linear, efficient power amplifier for high data rate wireless applications is presented. The linearity is greatly improved by adding an auxiliary amplifier to the main bipolar junction transistor (BJT) in a feed-forward approach to cancel out the non-linearity terms. The efficiency enhancement is achieved using a switchable biasing and output(More)
A 1.6 GHz/ 4.8 GHz fractional-N frequency synthesizer in 0.18-μm CMOS technology is presented in this paper. Its purpose is to generate the local oscillator (LO) signals for a fully integrated S-Band transceiver with a direct-conversion receiver (RX) and a dual up-conversion transmitter (TX) to avoid the frequency pulling problem. The synthesizer(More)
A receiver architecture covering 54-864 MHz and suitable for tolerating large interferers is presented in 0.18 μm CMOS. It alleviates the problem of LO harmonics mixing with the aid of a heterodyne conversion, and by employing an active feedback, provides an IIP3 of better than +13.4 dBm, comparable with state-of-the-art. Noise canceling techniques(More)
  • 1