h parameter model Another model commonly used to analyze the BJT circuit parameter model h. This model is an equivalent circuit of a bipolar junction transistor and allows easy analysis of circuit behavior, and can be used to develop models more accurate. As shown, the term "x" in the model represents the BJT terminal depending on the topology used. For common-emitter mode the various symbols of the image take on specific values:
i
in
= Base current (i 
b) i or
= Collector current (i
c)
V
in
= Base-emitter voltage (V
) 
V or
= Collector-Emitter Voltage (V-
- And the parameters are given by h :
- ix h = h
- ie - The input impedance of the transistor (corresponding to the emitter resistance r and ). h
- rx = h re - represents the dependence of the curve I B - V
- BE of the transistor in the value of CE V . It is usually a very small value and is usually neglected (assumed zero). h
faith
- The current gain of the transistor. This parameter is usually referred to as h FE
- profit or direct current (DC
- β) in on the sheets. h ox = oe h - The output impedance of the transistor. This term is usually specified as an admittance and must be invested to make to impedance.
- As shown, the parameters have subscript lowercase h and thus represent the conditions of circuit analysis are with alternating currents. For current conditions of these sub-indices are expressed in capital letters. For common-emitter topology, an approximate h-parameter model is commonly used because it simplifies the circuit analysis. Therefore the parameters h h oe and re are ignored (they are taken as infinite and zero, respectively). Also note that the h-parameter model is only applicable to the analysis weak signals of low frequencies. For analysis of high frequency signals is not used this model because it ignores the capacitances between electrodes that come into play at high frequencies. Posted by: Emmanuel Angel
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