Yazar "Guvenc, Umut" seçeneğine göre listele

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    SiGe Subharmonic Mixer for Direct Conversion Receivers
    (IEEE, 2016) Guvenc, Umut; Palamutcuogullari, Osman; Yarman, Siddik
    A second harmonic mixer appropriate for direct conversion recievers is realized in 0.18 mu m SiGe technology. The realized topology offers a unique mechanism to prevent LO to RF leakage, thus, suppress the DC Offset voltage due to LO self mixing. The constant current consumption of the topology provides a proper isolation of the noise mixing operation from the supply lines. Large signal analysis of the topology is presented and the dependence of the conversion gain on the biasing conditions is investigated. Measurements are acquired to verify the conversion gain gathered from the analysis and the simulation results. According to measurement results, the conversion gain of the circuit is 35 dB and the second harmonic of LO to RF leakage is less than 70 dB.
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    Tunable Active Front-End Realized by Using Zero-IF Down and Up Converters for to be Used in Software Defined Radios
    (IEEE, 2017) Palamutcuogullari, Osman; Guvenc, Umut
    The proposed tunable Active BPF which is operating within 30-512 MHz band is realized by using the Zero-IF active Down and Up converters. The operating frequency of the circuit is adjusted by fixing the frequency of the LO which drives the both converters. The bandwidth of the circuit is adjusted by changing the band-width of the active Base-Band LPF which is placed between the two converters. The circuit behaves as a Low-Noise, Narrow-Band Tuned RF Front-End Amplifier with+17 dB Moderate Gain and High Selectivity. The input IIP3 is around 5dBm. A single stage NMOS common-gate balanced amplifier is situated at the input to provide the impedance matching and the sharp selectivity. The voltage-series reactive-capacitive feedback is applied to the first stage in order to raise its input impedance for the purpose of impedance matching at the input port as well as for improving its dynamic range and its bandwidth. Implemented in 0.18um CMOS process technology, a tunable, band-pass 30-to-512 MHz receiver front-end with achieves a maximum of 3.5 dB NF, +18 dB gain, +3dBm IIP3 across the operating band.