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    • 62. 发明授权
    • Portable radio device with direct conversion receiver including mixer down-converting incoming signal, and demodulator operating on downconverted signal
    • 具有直接转换接收器的便携式无线电设备,包括下变频输入信号的混频器,以及在下变频信号上操作的解调器
    • US06693977B2
    • 2004-02-17
    • US09855613
    • 2001-05-16
    • Hiroshi KatayamaKatsuaki AbeYasumi Imagawa
    • Hiroshi KatayamaKatsuaki AbeYasumi Imagawa
    • H03D300
    • H03D3/245H03D3/007
    • A direct conversion receiver includes a local oscillator for generating a first local oscillator signal having a variable frequency. A 90° phase shifter operates for shifting a phase of the first local oscillator signal by 90° to convert the first local oscillator signal into a second local oscillator signal. A first mixer operates for mixing a received RF signal and the first local oscillator signal. A second mixer operates for mixing the received RF signal and the second local oscillator signal. A first low pass filter processes an output signal of the first mixer. The first low pass filter has a controllable cutoff frequency. A second low pass filter processes an output signal of the second mixer. The second low pass filter has a controllable cutoff frequency. A demodulator recovers an information signal represented by the received RF signal from output signals of the first and second low pass filters. A frequency error detector operates for detecting an error between a frequency of a carrier of the received RF signal and the frequency of the first local oscillator signal in response to the information signal recovered by the demodulator. An oscillator controller operates for controlling the frequency of the first local oscillator signal in response to the error detected by the frequency error detector. A filter controller operates for controlling the cutoff frequencies of the first and second low pass filters in response to the error detected by the frequency error detector.
    • 直接转换接收机包括用于产生具有可变频率的第一本机振荡器信号的本地振荡器。 90°移相器用于将第一本地振荡器信号的相位移位90°以将第一本机振荡器信号转换为第二本机振荡器信号。 第一混频器用于混合接收的RF信号和第一本地振荡器信号。 第二混频器用于混合接收到的RF信号和第二本地振荡器信号。 第一低通滤波器处理第一混频器的输出信号。 第一个低通滤波器具有可控的截止频率。 第二低通滤波器处理第二混频器的输出信号。 第二低通滤波器具有可控的截止频率。 解调器从第一和第二低通滤波器的输出信号中恢复由接收的RF信号表示的信息信号。 频率误差检测器用于响应于由解调器恢复的信息信号来检测接收的RF信号的载波的频率与第一本地振荡器信号的频率之间的误差。 振荡器控制器用于响应于由频率误差检测器检测到的误差来控制第一本地振荡器信号的频率。 滤波器控制器用于响应于由频率误差检测器检测到的误差来控制第一和第二低通滤波器的截止频率。