Single-section high-pass filters are shown in Figs. 1A and 1B. These are the inverse of the LPF single-section filters in that the capacitors are in series with the signal path, and the inductors are across the signal path. The version in Fig. 1A is the t-filter configuration, and that in Fig. 1B is the pi-filter. The values for the components are found in Table 1.
1 (A) Three-element, T-section high-pass filter and (B) three-element, pi-section highpass filter.
Table 1. Filter design constants for Fig. 1A,1B
Example: Find the component values for a single-section high-pass filter with a cutoff frequency of 40 MHz.
t filter (Fig. 1A):
L1 = KL1/FMHz
L1 = 3.97/40 = 0.1uH
C1 = KC1/FMHz
C1 = 3180/40 = 79.5 pF
Pi filter (Fig.1B):
L1 = KL1/FMHz
L1 = 7.94/40 = 0.2uH
C1 = KC1/FMHz
C1 = 1590/40 = 40 pF.
Two section high-pass filters are shown in Figs. 2A (t-filter) and 2B (pi-filter), and the 1-MHz model constants are shown in Table 2.
2 (A) Five-element, T-section high-pass filter and (B) fiveelement, pi-section high-pass filter.
Table 2. Filter design constants for Fig. 2A,2B
