The output impedance of JFETs is similar in magnitude to that of conventional BJTs. On JFET specification sheets, the output impedance will typically appear as g os or y os with the units of mS. The parameter y os is a component of an admittance equivalent circuit , with the subscript o signifying an o utput network parameter and s the terminal ( s ource) to which it is attached in the model. For the JFET of Fig. 6.20 , g os has a range of 10 mS to 50 mS or 20 k (R = 1>G = 1>50 mS) to 100 k (R = 1>G = 1>10 mS). In equation form,