Based on the suppression of T-VCO output noise. The transfer function of LF can be expressed as a literature on PLL theory. The design of such a filter has been discussed in detail. This paper is designed and optimized by computer design simulation software (ADPLLs2002). The PD circuit of the OPLL system consists of a Gilbert circuit (Gilbert) and a mirror current source. The bandgap reference (BGR) current acts to keep the bandwidth of the OPLL loop stable. The mirrored current source converts the output signal of the Gilbert cell into a current. When the device is in the standby state, the reset switch is grounded and the PD output voltage is zero. When the OPLL loop is activated, the reset switch is turned off and the bias current charges the LF capacitor. The lock time of the loop is almost determined by the bias current value and the LF capacitance. Considering the frequency locking characteristics of the OPLL system, selecting the bias current phase IV, the simulation and test results of some circuits are based on the basic principles and methods given. The author has carried out a large number of system experiments and simulation work. The closed-loop transfer function of the OPLL system and the output spectral characteristics of the frequency converter are key technologies. The design optimization of the loop filter has a crucial impact on the former two.
According to requirements, the channel spacing of F(s) bandwidth f is doubled. The circuit structure used and the values ​​of the RC components given in Table 2, the simulation results of the OPLL system closed-loop transfer function (s). The 0 dB flat range of (s) is 200 kHz, which satisfies the requirements of information transmission. In order to clearly see the effect of the OPLL system on each frequency component, the 67.7 kHz monophonic sine wave signal is added to the I and Q terminals respectively, and modulated to the 1.4 GHz IF carrier frequency. After the OPLL system, the IF carrier is finally changed to the Ku-band of 14.202 GHz, the output spectrum of the OPLL inverter. In the case where the reference level REF = 12.3 dB, the measured level and the suppression effect of each frequency component are output.
Through the theoretical analysis, circuit simulation and experiment in this paper, we can see that OPLL has obvious advantages in realizing Ku-band upconverter, and the parasitic component of its output frequency can be effectively suppressed (-40dBc), and the output level is higher. (usually up to 10dBm). In addition, OPLL-based upconverters reduce the performance requirements of RF filters and power amplifiers, reducing the size and power consumption of wireless transmitters, and facilitating miniaturization. In this paper, the theory and implementation technology of OPLL used as Ku up-converter are studied in depth. However, there are still some problems in the research of this technology at home and abroad, both in theory and in implementation technology.
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