Development of a Wide-Band Intermediate Frequency Receiver to Minimize the Second Harmonic Signal

Abstract

In this study, an eight-channel wide-band intermediate frequency (IF) receiver with an S-band input frequency, an output frequency of 200 MHz, and a signal bandwidth of 160 MHz was developed. The performance measurement results of the IF receiver showed that the fundamental signal and the second harmonic signal were involved in the bandwidth of the IF receiver output. This was caused by the nonlinearity characteristics of the final stage amplifier. Therefore, the final stage amplifier was changed to a differential amplifier, and the circuit of the IF receiver was modified to reduce the second harmonic signal. After improvement, an IF receiver with a gain of 33 dB, Output 1 dB Gain Compression Point(OP1dB) of > 15.8 dBm, 3rd Output Intercept Point(OIP3) of > 25.7 dBm was developed.The second harmonic suppressions were in the range of −83.30 dBc to −75.19 dBc when the fundamental signal output power was −10 dBm. This result satisfied the requirement of the system for the second harmonic suppression that was lower than −70 dBc.

Relationship between Mechanical and Electrochemical Property in Silicon Alloy Designed by Grain Size as Anode for Lithium-Ion Batteries

“…However, over cycles, the oxidation curve for c-Li 15 Si 4 slowly decreased, and a new curve appeared around 0.3 V, which seems to show that the Li 15 Si 4 crystalline phase is diminished by the reduction of silicon reaction level and of silicon electrode capacity. 13,14,21 This research identified that, over each cycle, the curves at the 0.45 V section are reduced, and the curves at the 0.3 V section increase. This research identified that the capacity of the 873 K sample (Fig.…”

“…Thus, we can expect a good effect in improving the cycle life of LIB. 14,15 Debye-Scherrer Eq. 1 is to determine the average grain size through XRD peak analysis: 16…”

“…In short, while silicon alloy containing other elements has a lower initial reversible capacity than pure silicon electrode, inactive matrix of Si-alloy controls the volume change of silicon. 13,14 Namely, it has better performance in terms of capacity maintenance than pure silicon electrode.…”

“…The experimental process was done according to our previous studies. 13,14 As a reference sample microsized Si powder (99.9%, Taewon Scientific Co, KR) was prepared to compare with silicon alloy.…”