Graphic methaod to obtain CE configuration:

$h_{ie}=\dfrac{v_b}{i_b}\left.\right|_{vc=0}\\ =\dfrac{\alpha v_b}{\alpha i_b}\left.\right|_{V_{CE}}\\ slope=\dfrac{i_B(B)-i_B(A)}{V_{BE}(B)-V_{BE}(A)}$

From input char. curve of VCE=VCE1(constant), then target at QZ drawn will have a slope of 1/hie

∴ Reciprocal of slope of line AB=hie

Parameter hre:

$h_{re}=\dfrac{v_b}{v_c}\left.\right|_{i_b=0}=\dfrac{\Delta V_B}{\Delta V_C}\left.\right|_{i_b=constant}\\[2ex] =\dfrac{\alpha v_b}{\alpha i_b}\left.\right|_{I_B}=\dfrac{V_{B2}-V_{B1}}{V_{C2}-V_{C1}}$

From graph of input charac. hre can be determined as a ratio of change in base to emitter voltage to change in collector to emitter voltage. Graph Shown in 52 is used to determine hre. keeping IBQ  constant if change in collector to emitter voltage, $\Delta V_C=V_{CE3}-V_{CE1} $ then corresponding change in base to emitter voltage ΔVB is found to VBE3-VBE1

$\therefore h_{re}=\dfrac{V_{CE3}-V_{CE1}}{V_{BE3}-V_{BE1}}$

In practical ΔVCE is large as compared to ΔVBE & H is different to obtain a accurate value for hre graphically.

Parameter hfe:

$h_{fe}=\dfrac{i_c}{i_b}\left.\right|_{vc=0}=\dfrac{\Delta i_c}{\Delta i_b}\left.\right|_{i_b=constant}\\[2ex] =\dfrac{\alpha i_c}{\alpha i_b}\left.\right|_{I_B}=\dfrac{iC_2-iC_1}{iB_2-iB_1}\left.\right|_{vc}$

From the output char of a given transistor as shown in fig 5.3 hfe can be expressed as change in Δ IC to Δ IB. hfe is the most important hybrid parameter since H reflect the value of current game of trnsistor on which the amplification property of a transistor depends.

$h_{fe}=\dfrac{iC_2-iC_1}{iB_2-iB_1}\left.\right|_{vc}$

Parameter hoe:

$h_{oe}=\dfrac{i_c}{v_c}\left.\right|_{i_b=0}\\ =\dfrac{\alpha i_c}{\alpha v_c}\left.\right|_{i_b=0}$

Graphically, hoe can be determined by determining the slop of tangent drawn or Q point as shown in fig AB is the tangent line drawn on point Q. slope of line AB can give value of hoe.

$slope=\dfrac{i_c(B)-i_c(A)}{V_{CE}(B)-V_{CE}(A)}\left.\right|_{i_B}=\dfrac{\Delta i_c}{\Delta V_{CE}}\left.\right|_{i_B}$

hoe =slope of line or tangent AB.