| 摘要 |
PURPOSE: A squelch circuit is provided not to input a wrong data by detecting a signal of small level in a data section with controlling a squelch level of an input data. CONSTITUTION: Data of RX+ and RX- of an AC component passed a transformer(20) is outputted a VRX+, a VRX-, a V'RX+, a V'RX-, a V'RX+, and a VRX- having three kinds of DCs by a first and a second resistant driver units(21)(22). When a packet is started by inputting in a first and a second selecting units(23)(24), the VRX+, the VRX-, the V'RX+, the V'RX-, the V'RX+, and the VRX- outputted from the first and the second resistant driver units(21)(22) selects a VRX+' and a VRX-' by an outer signal(=low), and selects a VRX+' and a VRX-' by enabling with an inverter(29). In a VRX+sq and a VRX-sq selected by the first and the second selecting units(23)(24) and the VRX+ and the VRX- of the first and the second resistant units(21)(22), final outputted signals(RXO+, RXO-) become 'high' if the VRX+ and the VRX- are lager than the VRX+sq and the VRX-sq, and the RXO+ and the RXO- becomes 'low' if the VRX+ and the VRX- are smaller than the VRX+sq and the VRX-sq. Herein, an R4 and an R5 are a variable resistances to be controlled according to a squelch level. |
